Insertion devices (also called inserter or injector) are commonly used in the medical field for inserting medical devices, such as infusion sets, sensors and the like, through the skin of a patient in a more or less automated fashion.
Commonly, when using an inserter, the user, i.e. the patient or the treatment provider (e.g. nurse, doctor, relative, or the like) has to apply a force towards the surface of the skin of the patient in order to provide injection of the medical device (needle, cannula, sensor, and the like). This can cause physiological or psychological distress and/or discomfort, and may lead to inappropriate application of the medical device. Many people are afraid of sharp objects, such as injection needles and other penetrating devices, commonly used for medical treatment and therapy. This fear is often irrational, and it may hamper an appropriate medical treatment. For example in the case of self-medication, a lack of administration of an appropriate dose of a required medical composition can lead to complications, which may even be life-threatening. When treating diabetes, e.g. in juveniles, there is a risk that the required insulin-dose may not be self-administered due to irrational fear of the insertion needle, combined with a general lack of knowledge and awareness concerning the consequences of omitting the correct application of the device and dosage.
A further known issue with insertion of medical devices is the risk of contamination of the penetrating member before or during application. This can easily lead to the introduction of an infection to a patient, e.g. through a contaminated insertion needle. The longer such a needle is exposed, the higher the risk of accidental contamination, e.g. by touching the needle with a finger, bringing the needle in contact with an unclean surface, or by airborne contamination, aerosol contamination and the like. Depending on the nature of the contamination (e.g. comprising virus, bacteria, fungus, yeast and/or prion) combined with the general health status of the patient, the resulting infection can rapidly turn into a life threatening situation.
Finally, it is well known that contact with an infected, used needle especially in hospital environments can be life-threatening, and the risk of accidental exposure to contaminated material in the form of a used insertion needle must be minimized.
The document WO 2002/002165 discloses a needle device having a needle retraction mechanism retracting the needle upon removing the device from a skin surface. The needle device comprises a penetrating member N connected to transformation means (44), an actuator (40) comprising guiding means restricting the movement of the transformation means and guiding the penetrating member N from a first to a second position in the direction of insertion towards the injection site. Further, the needle device comprises a stationary housing (20) provided with guiding means restricting the movement of the actuator (40). The actuator (40) and the attached needle N move in the same direction namely the direction of insertion. According to the present invention the penetrating part moves relative to the moving part and the moving part is fully separated from the penetrating part after insertion. This makes it possible to push the moving part in one direction with a simple spring mechanism while the penetrating member is guided to the injection site in the insertion direction. Separating the units and the direction optimises the possibility of individual control of each part when it comes to e.g. velocity and acceleration.
Thus, there is an obvious need in the art for a robust, reliable, accurate, safe, hygienic, and user friendly insertion device, which addresses the issues discussed above.
The document PCT/EP2009/051974 describes an insertion device of similar type as the invention. This document relates to an insertion device comprising                a penetrating member connected to transformation means,        a moving part comprising guiding means which guiding means restrict the movement of the transformation means and guide the penetrating member from a first to a second position in a first direction, i.e. the direction of insertion, towards the injection site, and        a stationary housing comprising guiding means which guiding means restrict the movement of the moving part. The guiding means guide the moving part in a second direction which is linear and different from the first direction i.e. the direction of insertion.        
According to this insertion device the length of the subcutaneously positioned part which can be inserted is defined by the height of the moving part as the subcutaneously positioned part cannot travel any longer than the height of the illustrated moving part.